I have been studying the screencaps all morning and i think i might be seeing a different kind of proof that De actually does choose Jason.
1. For the theory to work, we must assume that a different limo takes Jesse home. Cupcakes has some great evidence working there.
2. In one screencap, Jason arrives and they share a passionate kiss.
We know he is just arriving because he comes from afar and they both have to stretch out to greet each other. He is on the right. We know the picture isn't flipped because of where her hair is parted. She has her left hand in a fist, fingers flat, much as you would if you were holding something small in your hand, but not as you would hold your hand if you were getting ready to punch something (fingers curled).
3. Then, in the screencap on the top of page 20, Jason's face is to the water; hers is looking off the platform toward the entrance. Meaning, they have made a 90 degree turn by now.
He is pushing her gently to walk backward, with his hand down on her hip. He's getting her into position to make a proposal. He has to work at this, and she is going along.
Four thoughts here -
a) the producers, knowing who DeAnna is going to pick, have probably told Jason, "if you're going to propose, you need to be on her left so the camera can see you put the ring on her hand. Jesse was apparently not given this same counsel, because he stays on the right during the proposal, and it appears from her hair and white hair clip that this has not been flipped.
b) if Jason is sensing any bad news from DeAnna, he's not going to re-position her so her left hand is to the camera when he proposes, but he is re-positioning her, so he's feeling a good vibe,
c) By the time Jason is turning DeAnna, we can assume some time has gone by since the initial kiss, and it's in that time that she gave him the right vibe. Specifically, i agree with another poster that the big clue she gave him that it was OK to propose was asking him to put the necklace on her. We see in the full establishing shot she is wearing only earrings and a deep v-neck, strapless dress. Her neck is very bare, and usually when you go without a necklace with a gown, you wear a bracelet. She wears neither. She might have even chosen the dress because it perfectly shows off a necklace. Blowing up the turn shot, where you can see her neck, it's not conclusive (we need an HD screencap), but it does appear she's now wearing a necklace - there's a very distinct shadow with something hanging, like a heart or sand dollar pendant.
4. In the next shot, when Jason goes down on one knee, she is fully turned 180 degrees from the initial kiss. We know the picture isn't flipped because of the part in her hair.
Her two hands are now holding Jason's - she no longer has anything in her hand, and she's leaning in to what he's about to do. She's allowed Jason, or helped him, put her in the right place for the cameras. She didn't allow this for Jesse.
5. Then there is a shot where they are kissing, Jason still on the left. This is the infamous shot where the rose and ring appear to have been blurred out. This kiss
must be after the proposal, because the photo is not flipped - her hair is properly parted. So, in sequence, they kiss to greet (he's on the right), he turns her, he's finally on the left, he goes down on one knee, he stands up, and they kiss again, and he's still on the left. If she rejected him, she wouldn't be kissing him after the fact.
6. When Jason gives her that final kiss, there are pink flowers behind them. There are no pink flowers on the platform. The only other time you can find pink flowers is in Jesse's "welcome" kiss.
Here, below:
But if you look at that Jesse welcome picture carefully, they are not standing on the ceremony platform.
They are in the grass, and they are closer to the water. So, if you think of it differently, the pink flowers explain both couples leaving the platform and walking somewhere else, and to me, that helps me see that the kiss to Jesse is actually a goodbye kiss. 
They're standing in the grass, he doesn't go for her lips, she looks over at him to make sure he's OK (but she's not going in for a kiss as we assumed) But Jason's kiss, after the ceremony, still has passion, and they have blurred out the ring and the rose.
7. No matter what the explanation is for the pink flowers and the blurring is, one thing is clear, which makes it all conclusive (to me, anyway): De and Jason share two longer, lip-locked, passionate kisses at the final ceremony. Even if Jesse and De had a better kiss that was edited out - his actual greeting kiss, for example - it is hard to explain how there could be two DeJay passionate kisses in one ceremony if she was letting him go. You don't keep kissing the guy who's leaving, once facing one way, and once facing another way.
I'm new at this - so bear with me!